The hooded/berkshire gene is one gene. Homozygous form is hooded, heterozygous form is Berkshire.

So for a hooded parent to have berkshire offspring, one parent must be berkshire or self. Since you also got the homozygous hooded form then you know the other parent cannot be a self, hence must be berkshire. It gets complicated with the different forms of berkshire like Irish and vari -berk but that's basically how it works.